I notice that system indices in Elasticsearch have "index.number_of_replicas": "0" and this cannot be updated. Is there a reason why this cannot be set to 1 (or more) and how safe is it to have no replicas for system indices from a high availability point of view? How can we mitigate system index failures?
They should be set as auto-expanding using the index.auto_expand_replicas
setting in the relevant template.
How many data nodes do you have in your cluster?
We are investigating two types of clusters: 2 clusters with 3 nodes and 1 having 6 nodes. The 2 clusters having 3 nodes are in separate data centers and will be used as multi cluster HA implementation (Active-Passive).
The single 6 node cluster has 3 nodes in each datacenter and should act as Active-Active HA solution.
I know how to deal with zones for replicas, cluster replication etc, but I am not sure how-to HA the system indices in each solution.
Mayve allsystem indeices are secretly available on all (data) nodes? That would be nice!
OK, I close this topic. Apparently when you start with multi node clusters, all system indices do have replicas. The settings show the following attributes:
"index.auto_expand_replicas": "0-1",
"index.number_of_replicas": "1"
It seems that system indices high availability is taken care of automatically. Great!
Note that (as per the docs) this doesn't work as a HA solution:
You cannot configure a two-zone cluster so that it can tolerate the loss of either zone because this is theoretically impossible.
This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.